test: stabilize flaky retain and load batch tests

- test_retain.py: pin fact_type_override="world" on retains that later
  filter recall by fact_type=["world"]; the LLM was classifying facts as
  "experience" non-deterministically, returning 0 recall results.
- test_load_large_batch.py: add disable_observations fixture so inline
  consolidation (SyncTaskBackend) doesn't run during load tests — the
  pool-under-load mock wasn't handling scope="consolidation" and was
  timing out under 10 concurrent retains.
- test_load_large_batch.py: mark the file with xdist_group so the heavy
  load tests don't contend for CPU/memory with other parallel workers.

Author: nicoloboschi

hindsight-api-slim/tests/test_load_large_batch.py

@@ -25,6 +25,8 @@
 
 logger = logging.getLogger(__name__)
 
+pytestmark = pytest.mark.xdist_group("load_batch_tests")
+
 
 def generate_content(char_count: int) -> str:
     """Generate realistic content of approximately char_count characters."""
@@ -117,9 +119,18 @@ async def memory_with_mock_llm(self, pg0_db_url, embeddings, cross_encoder, quer
         except Exception:
             pass
 
+    @pytest.fixture
+    def disable_observations(self):
+        from hindsight_api.config import _get_raw_config
+        config = _get_raw_config()
+        original = config.enable_observations
+        config.enable_observations = False
+        yield
+        config.enable_observations = original
+
     @pytest.mark.asyncio
     @pytest.mark.timeout(300)  # 5 minute timeout
-    async def test_large_batch_500k_chars_20_items(self, memory_with_mock_llm, request_context):
+    async def test_large_batch_500k_chars_20_items(self, memory_with_mock_llm, request_context, disable_observations):
         """
         Test retaining a batch of 20 content items totaling ~500k chars.
 
@@ -283,7 +294,7 @@ async def mock_llm_call(*args, **kwargs):
 
     @pytest.mark.asyncio
     @pytest.mark.timeout(60)
-    async def test_db_connection_pool_under_load(self, memory_with_mock_llm, request_context):
+    async def test_db_connection_pool_under_load(self, memory_with_mock_llm, request_context, disable_observations):
         """
         Test that DB connection pool handles concurrent operations.
 

hindsight-api-slim/tests/test_retain.py

@@ -378,6 +378,7 @@ async def test_mentioned_at_vs_occurred(memory, request_context):
             content="Alice graduated from MIT in March 2020.",
             context="education history",
             event_date=conversation_date,  # When this conversation happened
+            fact_type_override="world",
             request_context=request_context,
         )
 
@@ -1149,6 +1150,7 @@ async def test_chunk_fact_mapping(memory, request_context):
             content=content,
             context="technical documentation",
             document_id=document_id,
+            fact_type_override="world",
             request_context=request_context,
         )